The line “Help me, Obi-Wan Kenobi, you’re my only hope” never held so much meaning.

The original “Star Wars’’ movie was nearly banished to a galaxy far, far away by a mutinous production crew — only to be saved at the last minute by legendary Obi-Wan actor Sir Alec Guinness, a new tome reveals.

Guinness, who portrayed the galactic icon in the 1977 classic, lent creator/director George Lucas the “credibility” he desperately needed to keep his staff of malcontents in line, set designer Roger Christian writes in his memoir “Cinema Alchemist.”

The crew had turned on Lucas during filming, and the mutiny had gotten so bad that the studio, 20th Century Fox, had to fly in an executive to stage an emergency intervention, said Christian, 72, who invented the light saber and the original model for the droid R2D2.

But once Sir Alec showed up, he proved to be a Jedi master of diplomacy, wowing everyone with his “complete mastery as an actor’’ and professionalism by refusing to talk bad about anyone, turning the tide on the production, Christian said.

“Science fiction was at its lowest ebb at the box office,’’ noted the designer, who also created sets for “Alien’’ and “Life of Brian.’’

“When Alec turned up — always on time, always polite — it gave a credibility to George that he might not have had without someone of Alec’s stature.”

The disgruntled crew was impressed by Guinness right out of the gate, Christian said.

“The first shot ever was in the valley when Luke Skywalker and R2D2 have been zapped,’’ he said. “Alec rolled in the dirt before his first scene because he wanted the patina on his costume to be real. No one asked him to do that.”

But Guinness’s on-set loyalty couldn’t have come from a more unlikely source.

In his own memoirs, he dissed the flick as a “fantasy world of second-hand childish banalities’’ and admitted to pals that he did it only for the dough.

“New rubbish dialogue reaches me every other day on wodges of pink paper — and none of it makes my character clear or even bearable,’’ Guinness groused. “I just think, thankfully, of the lovely bread, which will help me keep going until next April.”